Mark Twain observed in 1897 that Australian history “does not read like history, but like the most beautiful lies; and all of a fresh new sort, no mouldy old stale ones”. That same year, Harold Lasseter, a 17-year-old horseman en route from Queensland to the Kalgoorlie goldfields, supposedly discovered a 14-mile reef bulging with gold in Central Australia, at the western end of the MacDonnell Ranges. It took 33 years, however, before he went public with his find, which he was unable to locate again. Fellow explorers wrote him off as a charlatan, and left him to his own devices. In 1931 his body was found in the desert, along with his diary. “What good a [gold] reef worth millions?” he lamented. “I would give it all for a loaf of bread.” The dying Lasseter drew a map leading to the reef for his wife. “It’s a bonanza,” he claimed.

Despite general condemnation of Lasseter as a liar and a fraud, over the years dozens of expeditions to find the reef have been launched by cranks and professionals alike. In 2000, Luke Walker read about Lasseter in Bill Bryson’s travel book Down Under. Originally from Birmingham, Walker, who had starred in the British soap Crossroads, studied documentary making at the Victorian College of the Arts. His debut, Beyond our Ken (2008), raised claims of child sex abuse by the founder of the Kenja cult, who committed suicide ten days before the film was due to premiere. What followed was a string of abandoned projects – would-be documentaries about Japanese whaling ships, American exorcists and “the Loch Ness monster of eels living on a trout farm”. Says Walker: “It was in desperation that I remembered the Lasseter story.”

As it turned out, another man had also invested his hopes in the same legend: Bob Lasseter, Harold’s son. Bob, six years old when his father perished, has spent most of his adult life trying to locate the reef. Now 87, the retired engineer and inventor lives in southern Sydney, where his modest home doubles as something of a museum honouring his father. Bob has also kept a scrapbook of newspaper clippings, with articles such as ‘Lasseter’s Golden Folly’. “The way they’ve printed it makes him look a bit idiotic,” Bob’s wife, Elsie, told Walker when they first met, three years ago. “I sure hope you’re a bit nicer.”

When that meeting took place, Bob was planning to head back into the desert. “I knew I had to go along with him,” Walker says. The two men set out for the Northern Territory in 2010, following Harold Lasseter’s map. Lasseter had described the reef as being near three hills that “look like women in sunbonnets talking to each other” and another that resembles “a Quaker’s hat”. But the thick mulga scrub made traversing the desert by vehicle almost impossible, inflicting puncture after puncture, and the men returned home defeated.

By this point Walker had sunk a year of his life and a good chunk of his savings into the film, Lasseter’s Bones (in limited release this month), and he has since driven into the desert three more times. “I can’t say if the gold exists,” Walker says, “because I’ve never seen it. But I can’t say it doesn’t exist either.”

Walker and Bob Lasseter are hardly alone. In 2011, Dick Smith, the businessman and aviator, conducted his own search based on a map he’d bought on eBay for $1500. There’s some strange sentiment, an almost theological streak, that makes people want to believe in lost treasure. Lasseter’s reef may be another beautiful lie but, as Twain went on, Australia’s history “is full of surprises and adventures, and incongruities, and contradictions, and incredibilities; but they are all true, they all happened.”

Mark Twain observed in 1897 that Australian history “does not read like history, but like the most beautiful lies; and all of a fresh new sort, no mouldy old stale ones”. That same year, Harold Lasseter, a 17-year-old horseman en route from Queensland to the Kalgoorlie goldfields, supposedly discovered a 14-mile reef bulging with gold in Central Australia, at the western end of the MacDonnell Ranges. It took 33 years, however, before he went public with his find, which he was unable to locate again. Fellow explorers wrote him off as a charlatan, and left him to his own devices. In 1931 his body was found in the desert, along with his diary. “What good a [gold] reef worth millions?” he lamented. “I would give it all for a loaf of bread.” The dying Lasseter drew a map leading to the reef for his wife. “It’s a bonanza,” he...